Question

所以，我的第一篇文章。

我学习Java。我遇到了一个问题。我想在尝试关闭窗口0帧时打开pop.up窗口。

所以，我插入这个。来自老师的示例代码。请检查一下在这里

private void formWindowClosing(java.awt.event.WindowEvent evt) {                                   
            int reply = JOptionPane.showConfirmDialog(this, "Really close?", "Close?", JOptionPane.YES_NO_OPTION);
            if (reply == JOptionPane.YES_OPTION) {
                this.dispose();
            if (reply == JOptionPane.NO_OPTION)
                this.setVisible(true);
            }
    }

它什么都不做。没有弹出窗口给我什么需求

Answer 1

您的方法很可能永远不会被调用。您需要使用WindowListener。以下是您设置的方式：

JFrame mainFrame = new JFrame(); //that's your frame

mainFrame.setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE) //enable windowlistener handling

mainFrame.addWindowListener(new WindowListener() { //you need to add a windowlistener

        @Override
        public void windowClosing(WindowEvent e) {
            formWindowClosing(e); //call your method
        }

        @Override 
        public void windowOpened(WindowEvent e) {}

        @Override 
        public void windowClosed(WindowEvent e) {}

        @Override 
        public void windowIconified(WindowEvent e) {}

        @Override 
        public void windowDeiconified(WindowEvent e) {}

        @Override 
        public void windowActivated(WindowEvent e) {}

        @Override 
        public void windowDeactivated(WindowEvent e) {}

    });

当程序请求退出时，这将调用您的结束方法。

Answer 2

我使用NetBeans平台。所以我的代码如下：

package my.exercise21;

导入javax.swing.JOptionPane;

/ ** * * @author管理员 * / 公共类Exercise21扩展了javax.swing.JFrame {

/**
 * Creates new form Exercise21
 */
public Exercise21() {
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jMenuBar1 = new javax.swing.JMenuBar();
    jMenu1 = new javax.swing.JMenu();
    jMenuItem1 = new javax.swing.JMenuItem();

    setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);

    jMenu1.setText("File");

    jMenuItem1.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_X, java.awt.event.InputEvent.CTRL_MASK));
    jMenuItem1.setText("Exit");
    jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jMenuItem1ActionPerformed(evt);
        }
    });
    jMenu1.add(jMenuItem1);

    jMenuBar1.add(jMenu1);

    setJMenuBar(jMenuBar1);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 400, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 279, Short.MAX_VALUE)
    );

    pack();
}// </editor-fold>                        

private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
    dispose();
    // TODO add your handling code here:
}                                          

private void formWindowClosing(java.awt.event.WindowEvent evt) {                                   
        int reply = JOptionPane.showConfirmDialog(this, "Really close?", "Close?", JOptionPane.YES_NO_OPTION);
        if (reply == JOptionPane.YES_OPTION) {
            this.dispose();
        if (reply == JOptionPane.NO_OPTION)
            this.setVisible(true);
        }
}   

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(Exercise21.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(() -> {
        new Exercise21().setVisible(true);
    });
}

// Variables declaration - do not modify                     
private javax.swing.JMenu jMenu1;
private javax.swing.JMenuBar jMenuBar1;
private javax.swing.JMenuItem jMenuItem1;
// End of variables declaration

}

Answer 3

我想我的问题在于没有调用JOptionPane库

Answer 4

我刚刚解决了这个问题。感谢您的有益参与和您的善意。

/*
 * To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package my.exercise21;

import javax.swing.JOptionPane;

/**
*
* @author Administrator
*/
public class NewJFrame extends javax.swing.JFrame {

/**
 * Creates new form NewJFrame
 */
public NewJFrame() {
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jMenuBar1 = new javax.swing.JMenuBar();
    jMenu1 = new javax.swing.JMenu();
    jMenuItem1 = new javax.swing.JMenuItem();

    setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);
    setTitle("Exercise 2.1");
    setCursor(new java.awt.Cursor(java.awt.Cursor.NW_RESIZE_CURSOR));
    addWindowListener(new java.awt.event.WindowAdapter() {
        public void windowClosed(java.awt.event.WindowEvent evt) {
            formWindowClosed(evt);
        }
        public void windowClosing(java.awt.event.WindowEvent evt) {
            formWindowClosing(evt);
        }
    });

    jMenu1.setText("File");

    jMenuItem1.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_X, java.awt.event.InputEvent.CTRL_MASK));
    jMenuItem1.setText("Exit");
    jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jMenuItem1ActionPerformed(evt);
        }
    });
    jMenu1.add(jMenuItem1);

    jMenuBar1.add(jMenu1);

    setJMenuBar(jMenuBar1);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 400, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 279, Short.MAX_VALUE)
    );

    pack();
}// </editor-fold>                        

private void formWindowClosed(java.awt.event.WindowEvent evt) {                                  
    // TODO add your handling code here:
}                                 

private void formWindowClosing(java.awt.event.WindowEvent evt) {                                   
    int r = JOptionPane.showConfirmDialog(this, "Really close?", "Close?", JOptionPane.YES_NO_OPTION);
    if (r == JOptionPane.YES_OPTION) {
            dispose(); // This closes the program
        if (r == JOptionPane.YES_OPTION)
            setVisible(false); // This just hides the window but program keeps running.
    }// TODO add your handling code here:
}                                  

private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
    dispose();        // TODO add your handling code here:
}                                          

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new NewJFrame().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JMenu jMenu1;
private javax.swing.JMenuBar jMenuBar1;
private javax.swing.JMenuItem jMenuItem1;
// End of variables declaration

}

帧关闭命令_variable

4 个答案: